Abstract: This paper took Guizhou’s main chili varieties‘Layan 102’and‘Sujiao No.5’as test materials；conducted field positioning experiments at 5 nitrogen application levels of 0，70，140，210 and 280 kg·hm^-2 for 2 consecutive years．According to the relationship between above-ground dry mass and nitrogen concentration，the paper established a critical pepper nitrogen concentration dilution curve model and evaluated its feasibility in diagnosis of nitrogen nutrition in pepper．The results showed that the above-ground nitrogen concentration in pepper plants decreased gradually as the fertility process advances，the dry weight on the rise．A unified N_c curve model for 2 pepper varieties was established：N_c = 4.39PDM^-0.28，R² was 0.93．Model test result showed RMSE was 0.26 and n-RMSE was 10.08%．And there was a significant linear relationship between the simulated value and measured value，indicating model had a better stability．The nitrogen nutrition index（NNI）calculated based on N_c curve increased with the increase of nitrogen application quantity，and the variation range of NNI was 0.55-1.27 under different years，varieties，nitrogen application quantity and growth period．Even the correlation between NNI and relative yield（RY）was linear regression，reaching an extreme significant level．Comprehensive considering the pepper yield and NNI，210 kg·hm^-2 was recommended as the suitable nitrogen application quantity for pepper in Guizhou region．

Key words: pepper, critical nitrogen concentration dilution curve model, nitrogen nutrition index, nitrogen diagnosis

摘要： 以贵州主栽辣椒品种辣研102、苏椒5号为试材，进行0、70、140、210、280 kg·hm^-2 5个施氮水平的连续两年田间定位试验，根据植株地上部干质量和氮浓度的关系，构建辣椒临界氮浓度稀释曲线模型，并评价其在辣椒氮素营养诊断研究中的可行性。结果表明，随生育进程的推进，辣椒植株地上部氮浓度逐渐降低，干质量呈升高趋势，构建了2个辣椒品种统一的N_c曲线模型：N_c = 4.39PDM^-0.28，R²为0.93。模型检验结果RMSE为0.26，n-RMSE为10.08%，且模拟值与实测值之间呈显著的线性关系，表明模型稳定性较好。基于N_c曲线推算的氮营养指数（NNI）随施氮量的提高而增加，不同年份、品种、施氮量和生育时期下NNI变化范围为0.55～1.30，且NNI与相对产量（RY）呈线性回归关系，相关性达到极显著水平。综合考虑辣椒产量及NNI，推荐贵州地区辣椒较适宜的施氮量为210 kg·hm^-2。

关键词: 辣椒, 临界氮浓度稀释曲线模型, 氮营养指数, 氮素诊断